Acrylic/lactam resin composition and method of production same

ABSTRACT

An acrylic/lactam monomer based polymeric resin is provided which has excellent weatherability, outstanding transparency and optical clarity, improved heath and solvent resistance, as well as improved impact strength. The acrylic/lactam monomer based polymeric resin is formulated by the catalytic activation at ambient temperature of a polymerization syrup which contains from about 300 to about 2970 parts by volume of an acrylic monomer, from about 30 to about 2700 parts by volume of a lactam monomer, from about 0.3 parts to about 40 parts by volume of a mercaptan chain transfer agent and from about 0.3 to about 40 parts by volume of a crosslinking agent capable of crosslinking the acrylic monomer and the lactam monomer. To prevent further polymerization of the polymeric constituents of the polymerization syrup, as well as to enhance the shelf life of the polymerization syrup, an effective amount of a polymerization inhibitor and an ultraviolet light stabilizer are incorporated into the polymerization syrup. The crosslinking of the acrylic monomer and the lactam monomer is carried out at ambient temperature and atmospheric pressure.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application under 37 CFR 1.60 ofapplication Ser. No. 08/405,118, filed Mar. 16, 1995, entitled"ACRYLIC/LACTAM RESIN COMPOSITIONS AND METHOD OF PRODUCING SAME"; whichis a divisional application of U.S. Ser. No. 08/136,632, filed Oct. 14,1993, entitled "ACRYLIC/LACTAM RESIN COMPOSITIONS AND METHOD OFPRODUCING SAME", now U.S. Pat. No. 5,399,593, issued Mar. 21, 1995.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to polymeric resin compositions, and moreparticularly, but not by way of limitation, to acrylic/lactam monomerbased resin compositions curable at ambient temperatures and atmosphericpressure. In one aspect the present invention relates to apolymerization syrup formulated at ambient temperature and atmosphericpressure from an acrylic monomer and a lactam monomer which, uponactivation, provides a resinous composition curable at ambienttemperature and atmospheric pressure.

2. Brief Description of Prior Art

Acrylic resins formed predominantly of methyl methacrylate haveheretofore been known. Because acrylic resins formed of methylmethacrylate are linear polymers, the polymers have exhibited goodweatherability and transparency. However, such polymers have sufferedfrom disadvantages in that they are deficient in resistance to heat,solvents, shock, and surface hardness. Because of these deficiencies,the prior art is replete with acrylic based resin compositions whereinthe base polymer, i.e., methyl methacrylate, is copolymerized withdissimilar monomers in an effort to overcome the before-stateddeficiencies of the acrylic resins.

While various resin compositions have been proposed for improving theheat and solvent resistance, as well as the surface hardness of acrylicbased resins, such modified resin compositions have a tendency to becomediscolored on heating and the desired properties of weatherability andoptical clarity are often sacrificed or reduced. Many of the problemsinherent with the prior art acrylic based resin compositions have beenovercome by the use of the polymerization syrups disclosed in my U.S.Pat. Nos. 5,023,313; 5,045,613; 4,945,122; and 5,243,003.

While acrylic based resin composition formulated in accordance with theteachings of my above-referenced U.S. Patents have generally exhibitedimproved physical and chemical properties, new and improved acrylicbased resin compositions are desired which exhibit improved color,optical clarity and impact resistance and which do not require postcuring, while at the same time possessing desired properties which allowsuch resin compositions to be foamed, filled with particulate fillers orcast into thick articles without air entrapment. It is to such anacrylic based resin composition that the present invention is directed.

SUMMARY OF THE INVENTION

In accordance with the present invention, acrylic/lactam polymericresins are provided having improved color, optical clarity, thermalshock and impact resistance, while at the same time possessing desiredproperties which allow such resin compositions to be foamed, filled withparticulate fillers or cast into thick articles without air entrapment.

The acrylic/lactam resin compositions of the present invention areproduced by activating a polymerization syrup formulated by admixing, atambient temperature and atmospheric pressure, from about 300 to about2970 parts by volume of an acrylic monomer, from about 30 to about 2700parts by volume of a lactam monomer, from about 0.3 parts to about 40parts by volume of a mercaptan chain transfer agent and from about 0.3to about 40 parts by volume of a crosslinking agent capable ofcrosslinking the acrylic monomer and the lactam monomer. The resultingadmixture is maintained at ambient temperature and atmospheric pressurefor a period of time effective to produce a polymerization syrup havinga polymeric constituent of a desired molecular weight. To preventfurther polymerization of the polymeric constituents of thepolymerization syrup, as well as to enhance the shelf life of thepolymerization syrup, an effective amount of a polymerization inhibitorand a ultraviolet light stabilizer are incorporated into thepolymerization syrup.

To produce a polymeric resin from the polymerization syrup, thepolymerization syrup is first initiated or activated so as to permitcatalytic activation of the polymerization syrup. If desired, aparticulate filled resin composition can be provided by incorporatingfrom about 10 to about 90 parts by weight of a particulate filler intothe catalyst initiated polymerization syrup.

An object of the present invention is to provide an acrylic/lactam resincomposition having improved color, optical clarity and thermal shock andimpact resistance.

Another object of the present invention, while achieving thebefore-stated object, is to provide an acrylic/lactam resin compositionwhich does not require post curing, while at the same time possessingdesired properties which allow such resin compositions to be foamed,filled with particulate fillers or cast into thick articles without airentrapment.

Yet another object of the present inventions, while achieving thebefore-stated objects, is to provide a polymerization syrup for anacrylic/lactam resin composition which, when activated, is curable atambient temperature and atmospheric pressure.

Other objects, advantages and features of the present invention willbecome apparent upon reading of the following detailed description inconjunction with the appended claims.

DETAILED DESCRIPTION

The present invention provides an acrylic/lactam monomer basedpolymerization syrup which, upon activation produces a polymeric resincomposition curable at ambient temperature and atmospheric pressure. Thepolymerization syrup is formulated by admixing, at ambient temperatureand atmospheric pressure, an acrylic monomer, a lactam monomer, amercaptan chain transfer agent and a crosslinking agent, and maintainingthe resulting polymerization admixture at ambient temperature andatmospheric pressure for a period of time effective to produce apolymerization syrup having a desired viscosity.

The amount of the acrylic monomer, the lactam monomer, the mercaptanchain transfer agent and the crosslinking agent employed in theformulation of the polymerization syrup can vary widely, and willgenerally depend on the properties desired in the polymeric resinproduced from the polymerization syrup. Generally, however, thepolymerization mixture contains from about 300 to about 2970 parts byvolume of an acrylic monomer, from about 30 to about 2700 parts byvolume of a lactam monomer, and minor effective amounts of a mercaptanchain transfer agent and an effective amount of a crosslinking agentcapable of crosslinking the acrylic monomer and the lactam monomer.

Once the polymerization syrup containing a polymeric constituent of adesired molecular weight has been produced, an effective amount of apolymerization inhibitor is incorporated into the polymerization syrupto prevent further polymerization of the polymeric constituent, as wellas to enhance the shelf life of the polymerization syrup.

In formulating the polymerization syrup of the present invention, anysuitable acrylic monomer represented by the formula ##STR1## wherein Ris an alkyl moiety containing 1 to about 18 carbon atoms, more desirablyfrom 1 to 8 carbon atoms, can be employed as the acrylic monomer,provided that the acrylic monomer is a liquid at ambient temperature andatmospheric pressure and is capable of crosslinking with the lactammonomer. Examples of alkyl moieties satisfying the definition for R ofthe before-described formula include methyl, ethyl, propyl, butyl,pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl,tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl and the like.Examples of acrylic monomers satisfying the above-defined formulainclude methyl methacrylate, ethyl methacrylate, n-butyl methacrylate,2-ethylhexyl methacrylate, cyclohexyl methacrylate, ω-hydroxyalkylmethacrylates, and the like.

The lactam monomers which can be employed in the formulation of thepolymerization syrup of the present invention are the lactam monomerswhich are compatible with the above-defined acrylic monomers, which arecapable of crosslinking with such acrylic monomers at ambienttemperature and atmospheric pressure and, when admixed with the acrylicmonomer, produces a liquid mixture. Generally, lactam monomerscontaining 3 to 12 or more carbon atoms in the lactam ring satisfy thebefore-stated requirements for lactam monomers which can be employed inthe formulation of the polymerization syrup of the present invention.Examples of such lactam monomers are pyrrolidone, piperidone,ε-caprolactam, γ-caprolactam, enantholactam, caprylolactam andlaurolactam.

The amount of the mercaptan chain transfer agent employed in theformulation of the polymerization syrup of the present invention canvary widely but will generally be present in an amount of from about 0.3to about 40 parts by volume per 3000 parts by volume of the acrylic andlactam monomers. Any mercaptan capable of functioning as a chaintransfer agent for the monomeric constituents of the polymerizationsyrup can be employed, such as, isooctyl-3-mercaptopropionate, n-dodecylethylene glycol dimercaptoacetate, n-butyl mercaptopropionate, n-octylmercaptan, n-dodecyl mercaptan and the like.

The amount of crosslinking agent required to effect the desiredcrosslinking of the acrylic and lactam monomers is generally from about0.3 to about 40 parts by volume per 3000 parts by volume of the acrylicand lactam monomers, the required amount depending on the efficiency ofthe crosslinking agent. That is, for a strong crosslinking agent theconcentration of the crosslinking agent required will be less than whena weak crosslinking agent is selected.

Any crosslinking agent capable of effecting the desired crosslinking ofthe acrylic and lactam monomers at ambient temperature and atmosphericpressure can be employed as the crosslinking agent in the formulation ofthe polymerization syrup of the present invention. Such crosslinkingagents are well known in the art and include ethylene glycoldimethacrylate, allyl methacrylate, allylacrylate, ethylene glycoldiacrylate, polyethylene glycol dimethacrylate, diethylene glycoldimethacrylate, triethylene glycol dimethacrylate and the like.

As previously stated, the polymerization mixture of the acrylic monomer,the lactam monomer, the chain transfer agent and the crosslinking agentis maintained at ambient temperature and atmospheric pressure for aperiod of time effective to provide a polymerization syrup having adesired viscosity. The viscosity of the polymerization syrup, which isindicative of the molecular weight of the polymeric constituent presentin the polymerization syrup, can vary widely. However, for mostapplications, the polymerization mixture is maintained at ambienttemperature and atmospheric pressure until the polymerization syrup hasa predetermined viscosity within the range of from about 100 to about2000 centipoise.

The time required to produce a polymerization syrup having a desiredviscosity will vary widely depending upon the molecular weight desiredfor the polymeric constituent of the syrup. However, for mostapplications, a polymerization syrup having a polymeric constituent canbe achieved when the polymerization mixture is maintained at ambienttemperature and atmospheric pressure for a period of time of at leastabout 6 hours, and more desirably from about 24 to about 96 hours.

Once the desired amount of polymerization of the monomers present in thepolymerization mixture has occurred, the polymerization inhibitor isincorporated into the polymerization syrup to prevent furthercrosslinking or polymerization of the polymeric constituent. The amountof polymerization inhibitor incorporated into the polymerization syrupcan vary widely but will generally be in an amount sufficient to providethe polymerization syrup with from about 0.05 to about 20 parts byvolume of the polymerization inhibitor per 3000 parts by volume of thepolymerization syrup.

Any suitable polymerization inhibitor which is compatible with thepolymeric constituent of the polymerization syrup and capable ofpreventing further crosslinking of the polymeric constituent of thepolymerization syrup can be employed. However, desirable results havebeen obtained wherein the polymerization inhibitor is methyl ethylhydroquinone, 2-2hydroxy-5-methylphenylbenzotriazole or an alkylphosphites, such as triisooctyl phosphite, tris-2-chloroethyl phosphite,tributyl phosphite, triisopropyl phosphite, tris-2-ethylhexyl phosphite,trimethyl phosphite, triethyl phosphite and the like.

To enhance ultraviolet light stabilization of the polymerization syrup,it is often desirable to incorporate into the polymerization syrup aneffective minor amount of an ultraviolet light stabilizer. While theamount of ultraviolet light stabilizer employed can vary widely,generally the ultraviolet light stabilizer will be employed in an amountof from about 1 to about 20 parts by volume per 3000 parts by volume ofthe polymerization syrup.

Ultraviolet light stabilizers are well known in the art. Examples ofsuch ultraviolet light stabilizers are2-2'-hydroxy5-methylphenylbenzotriazole,2-(2H-benzotriazole-2-yl)-4-methylphenyl,2-(2'-hydroxy-3',6'-di-tert-amylphenyl)benzotriazole,beta-3-(3-(2H-benzotriazol-2-YL)-4-hydroxy-5-tert-butylphenyl),propionic acid, methyl ether, polyethylene glycol 300 and hinderedtertiary amines, such as bis(1,2,2,6,6-pentamethyl-4-piperidinyl)sebacate.

To produce a polymeric resin from the polymerization syrup of thepresent invention, an initiator is employed to initiate activation ofthe polymerization syrup. The polymerization syrup is initiated byexposure to ultraviolet light, heat or by the addition of from about0.05 to 20 parts by volume, based on 3000 parts by volume of thepolymerization syrup, of an initiator capable of initiating catalyticcuring of the resin. Examples of compounds which may be used as aninitiator are t-butyl peroxymaleic acid, N,N-dimethylacetoacetamide,mixtures of N,N-dimethylacetoacetamide and quaternary ammoniumcompounds, such as benzyl (C12-C18) alkyl dimethyl isopropanol, and thelike.

The initiated polymerization syrup can be activated and catalyzed by theaddition of a catalytic amount of a polymerization catalyst capable ofactivating the polymerization syrup, by the exposure to ultravioletlight or visible light or any combination thereof. Upon activation ofthe polymerization syrup, the resulting polymeric resin composition iscurable at ambient temperature and atmospheric pressure.

Any polymerization catalyst capable of activating the polymerizationsyrup can be employed in the preparation of the acrylic/lactam monomerbased resin compositions of the present invention. However, desirableresults have been obtained wherein the polymerization catalyst is atoluene solution containing 25% or 75% t-butyl peroxymaleic acid,t-butyl peroxymaleic acid, a mixture containing 90 weight percentt-butyl peroxymaleic acid, 5 weight percent2-(2'-hydroxy-5-methylphenyl)benzotriazole and 5 weight percent silicon,or a quaternary ammonium salt generally known in the industry as "fabricsofteners". When employing a toluene solution of t-butyl peroxymaleicacid as the polymerization catalyst, the concentration of the t-butylperoxymaleic acid can vary widely. However, desirable results have beenobtained where the toluene solution contains either 25% or 75% t-butylperoxymaleic acid.

The quaternary ammonium salts which may be used as the catalyst toactivate the polyacrylic/polylactam polymerization syrup of the presentinvention are generally known in the industry as "fabric softeners" andinclude the following:

Dialkyldimethylammonium chlorides, such as dicocodimethylammoniumchloride and ditallow dimethylammonium chloride;

Dialkyldimethylammonium methylsulfates;

Alkyltrimethylammonium chlorides, such as soya trimethylammoniumchloride, hydrogenated tallow trimethylammonium chloride,palmityltrimethylammonium chloride, cocotrimethylammonium chloride,tallow trimethylammonium chloride, and benzyltrimethylammonium chloride;and

Alkyldimethylbenzylammonium chlorides, such as dimethyl-alkyl (C14-C18)benzylammonium chloride and dimethylalkyl (C12-C16) benzylammoniumchloride.

The amount of the catalyst employed to catalyze the polymerization syrupcan vary widely and will be dependent to a large degree upon the acrylicand lactam monomers employed in the formulation of the polymerizationsyrup, as well as the nature of the catalyst chosen. However, generally,the amount of the catalyst employed to catalyze the polymerization syrupwill be an amount sufficient to provide from about 0.1 to about 15 partsby volume of the catalyst, based on the amount of monomers present in3000 ml of the polymerization syrup.

It may be desirable to incorporate an effective minor amount of aninternal mold release agent into the polymerization syrup to enhancemold release. The amount of the internal mold release agent can varywidely, but will generally be in an amount sufficient to provide fromabout 0.01 to about 2 parts by volume of the internal mold release agentper 3000 parts of the polymerization syrup.

Any suitable internal mold release agent can be employed provided thatthe internal mold release agent is compatible with the polymericconstituents present in the polymerization syrup. For example, desirableresults have been obtained wherein the internal mold release agent is asurfactant, and wherein the surfactant is an anionic or nonionicsurfactant which is compatible with the polyacrylic/polylactam copolymerand which does not reduce the transparency of the resulting polymericresin. Examples of suitable anionic surfactants include:

sodium alkyl sulfate, such as sodium octylsulfate, sodium laurylsulfate,sodium stearylsulfate;

sodium alkylbenzenesulfates, such as sodium dodecylbenzenesulfate;sodium alkylsulfonates, such as sodium cetylsulfonate and sodiumstearlylsulfonate;

sodium dialkyl sulfosuccinates, such as sodium dioctyl sulfosuccinate,and the like.

Examples of nonionic surfactants include:

polyethyleneglycol alkyl ethers, such as polyethyleneglycol oleyl ether,polyethyleneglycol lauryl ether, and the like;

polyethyleneglycol alkylphenyl ethers, such as polyethyleneglycolnonylphenyl ether;

higher fatty acid esters of polyethyleneglycol, such as oleic acid esterof polyethyleneglycol, stearic acid ester of polyethyleneglycol, lauricacid ester of polyethyleneglycol, and the like;

polyethyleneglycol polypropyleneglycol ether;

sorbitan fatty acid esters, such as sorbitan monolaurate, sorbitanmonostearate, and the like;

polyethyleneglycol sorbitan fatty acid esters, such aspolyethyleneglycol sorbitan monolauric acid ester, polyethyleneglycolsorbitan monooleic acid ester, phosphoric acid esters ofpolyethyleneglycol;

and phosphoric acid esters of alkylpolyethyleneglycol and the like.

The surfactants listed above are merely illustrative of anionic andnonionic surfactants which can be employed as the internal mold releaseagent in the formulation of the polymerization syrup of the presentinvention. However, desirable results have been obtained wherein thesurfactant is sodium dioctyl sulfosuccinate.

A polymerization syrup formulated as set forth above (whether sameincorporates the polymerization inhibitor and/or the mold release agent)provides a polymeric resin composition which can be cured, uponactivation, at ambient temperatures and atmospheric pressure. As willmore fully be described hereinafter, fillers can be incorporated intothe polymerization syrup to provide filled polymeric resins; and theactivated polymerization syrup can be foamed to produce foamed articles.

In formulating a particulate-filled article from the polymerizationsyrup of the present invention, a particulate material is admixed intothe polymerization syrup either prior to or during activation of thepolymerization syrup. The amount of the particulate matter admixed withthe polymerization syrup, as well as the nature of the particulatematerial, can vary widely and will depend to a large degree on theproperties and appearance desired in the cured article. Generally,however, when employing a filler to provide a filled resin composition,the amount of particulate filler admixed with the polymerization syrupwill be an amount sufficient to provide from about 10 to about 90 partsby weight of the particulate filler, based on the weight of thepolymerization syrup.

The particle size of the particulate filler can vary widely. However,the particulate filler will generally have an average particle size offrom about 1 to about 200 microns. Examples of particulated fillershaving the desired particle size which can be admixed with thepolymerization syrup of the present invention to produce particulatefilled resin compositions are aluminum trihydrate, carbon black, gypsum,graphite, iron oxides, and the like.

Foamed articles can also be produced from the polymerization syrup ofthe present invention. To produce a foamed article, effective amounts ofa foaming agent capable of foaming the catalyst activated polymerizationsyrup, an initiator and a catalyst are admixed with the polymerizationsyrup. Conventional foaming agents compatible with the polymericconstituents of the polymerization syrup can be employed; and, ifdesired, surfactants, fillers, pigments and fire retardant compounds mayalso be introduced into the polymerization syrup either before,simultaneous with or after the addition of the foaming agent, theinitator and the catalyst.

The polymerization syrups prepared in accordance with the presentinvention desirably have a viscosity in the range of from about 100centipoise to about 2000 centipoise. However, the viscosity of theparticular polymerization syrup employed will be dependent upon theproperties desired in the end product.

In the formulation of a foamed article, from about 70 to about 200 partsby weight of the polymerization syrup are admixed with from about 4 toabout 15 parts by weight of a foaming agent, from about 0.09 to 1.5parts by weight of an initiator and from about 0.5 to about 20 parts byweight of a catalyst for a period of time effective to provide asubstantially homogeneous foamable mixture. As will be apparent, theamount of the polymerization syrup employed in the foamable mixture willdepend on the desired properties and characteristics of the foamedarticle.

As previously stated, any suitable foaming agent compatible with thepolymerization syrup and capable of foaming the foamable polymerizationmixture may be employed. Illustrative of compounds which may be employedas the foaming agent in the preparation of foamed articles using thepolymerization syrup of the present invention are alkali metalhydroxides, alkali metal oxides, alkaline earth metal hydroxides,alkaline earth metal oxides, lead oxide, and a combination thereof.Examples of such alkali metal hydroxides are sodium hydroxide andpotassium hydroxide; and examples of such alkaline earth metalhydroxides and alkaline earth metal oxides are calcium hydroxide andmagnesium oxide.

Any suitable initiator which is compatible with the foamablepolymerization mixture can be employed as the initiator in theformulation of the foamable polymerization mixture. Examples ofcompounds which may be used as the initator are amines, such asN,N-dimethyl acetoamide, tertiary-butyl peroxymaleic acid, andquaternary ammonium salts.

Any suitable compound capable of activating the initiated foamablemixture can be used as the catalyst to produce a foamed article. Suchcatalysts have heretofore been described with reference to the catalyticactivation of the polymerization syrup.

If desired, a mold release agent, i.e. a surfactant, may also beincorporated into the foamable mixture to effect the "skin" of thefoamed article. The amount of surfactant employed can vary widely, butwill generally be an amount sufficient to provide the foamable mixturewith from about 0.5 to about 20 parts by weight of the surfactant.Examples of surfactants which may be incorporated into the foamablemixture are sodium dioctyl sulfosuccinate,polyoxyethylene-polyoxypropylene glycol, and N-vinyl-2-pyrrolidone andmixtures thereof.

Additionally, a particulate filler may be admixed into the foamablemixture to provide a filled foamed resin composition. The particulatefiller may be admixed or shear mixed into the foamable mixture; and theamount of particulate filler employed can vary widely depending on thedesired properties of the filled foamed resin composition. Generally,however, the amount of particulate filler incorporated into the foamablemixture is an amount sufficient to provide a filled foamable mixturecontaining from about 1 to about 300 parts by weight of the particulatefiller. The particle size of the particulate filler employed can varywidely and will again depend to a large degree on the properties desiredin the filled foam resin composition. Generally, however, theparticulate filler will have a particle size of from about 1 to about200 microns, and more desirably an average particle size of from about 1to about 100 microns.

Any particulate filler compatible with the foamable mixture can beemployed as the particulate filler. Examples of such particulate fillersare alumina trihydrate, carbon black, graphite, gypsum, granite, ironoxide, glass beads, mixtures thereof and the like.

Fire retardants may also be incorporated into the filled foamablemixture if desired. The particular fire retardant, as well as the amountof such fire retardant incorporated into the filled foamable mixture,will depend to a large degree on the properties and characteristicsdesired of the filled foamed resinous composition and the effect uponthe foaming properties of the foamable mixture. Generally, however, theamount of fire retardant compound incorporated into the filled foamablemixture is an amount sufficient to provide from about 2 to about 40parts by weight of the fire retardant compound in the filled foamablemixture. Examples of fire retardants which are suitable forincorporation into the filled f0foamable mixture are triphenylphosphate, decabromide phenyl oxide, and tris (2-chloroethyl) phosphite.

Pigments may also be incorporated into the filled foamable mixture. Anysuitable pigment can be employed provided that the pigment is compatiblewith the filled foamable mixture. Such pigments are well known in theart. Thus, no further comments concerning such pigments or their use isbelieved necessary to enable one to practice the inventive conceptdisclosed herein.

Articles produced from the foamable mixture as well as the filledfoamable mixture have many desirable uses and qualities, includingimproved physical and chemical properties. Further, such articles haveexhibited improved compressive strength, impact resistance, surfacehardness, weatherability, chemical and stain resistance and the abilityto drive a nail into the foamed resinous composition because of the"wood-like" interior cellular structure.

In order to further illustrate the present invention, the followingexamples are given. However, it is to be understood that the examplesare for illustrative purposes only and are not to be construed aslimiting the scope of the subject invention.

EXAMPLE I

A polymerization syrup was prepared by admixing the followingconstituents:

2500 ml of methyl methacrylate monomer

400 ml of ε-caprolactam monomer

10 ml of isooctyl-3-mercaptopropionate

10 ml of allylmethacrylate

The resulting mixture was maintained at ambient temperature andatmospheric pressure for about 78 hours so as to provide apolymerization having a viscosity of about 330 centipoise. The viscosityof the polymerization mixture was periodically measured so that themolecular weight of the polymeric constituent in the polymerizationsyrup could be determined. When the desired viscosity had been achieved,(i.e., 330 centipoise), the polymerization syrup was then stabilized bythe addition of 5 ml tris-2-chloroethyl phosphite, a polymerizationinhibitor; and 13 ml of 2-2'-hydroxy-5-methylphenylbenzotriazole wasthen added to the polymerization syrup to enhance ultraviolet lightstabilization.

The polymerization syrup so produced was then placed in a glasscontainer, sealed and stored at ambient temperature and atmosphericpressure. Examinations of the syrup were conducted to determine theintegrity of the polymerization syrup during storage. No deteriorationof the polymerization syrup was detected during storage periods of up tosix (6) months. Thus, the polymerization syrup produced exhibitedexcellent shelf life and one does not need to refrigerate thepolymerization syrup during storage in order to maintain the integrityof the polymerization syrup.

EXAMPLE II

A polymerization syrup formulated in accordance with the procedures ofExample I was catalytically activated by the addition of about 3 ml of atoluene based solution containing 25 weight percent t-butyl peroxymaleicacid. The catalyzed polymerization syrup was then poured into molds ofvarious configurations and thicknesses and allowed to cure for about 30minutes at ambient temperature and pressure. The peak exothermtemperature was monitored during curing and it was noted that thethicker the mold, the higher the peak exotherm temperature.

After curing, the articles were removed from the molds and examined.Each of the articles exhibited improved color, optical clarity andimpact resistance. Further, the thick articles were substantially bubblefree, indicating no air entrapment during curing.

EXAMPLE III

A polymerization syrup was formulated in accordance with the procedureof Example I with the exception that about 5 ml ofmethylethylhydroquinone was employed as the polymerization inhibitor inplace of the tris-(2-chloroethyl) phosphite. The polymerization syrupcontaining the methylethylhydroquinone was placed in a dark glasscontainer, sealed and stored at ambient temperature and atmosphericpressure. Examinations of the syrup were conducted to determine theintegrity of the syrup during the storage period. No deterioration ofthe syrup was detected during a three month storage period.

The polymerization syrup was then removed from storage and catalyticallyactivated by the addition of about 3 ml of a toluene based solutioncontaining 75 weight percent t-butyl peroxymaleic acid. The catalyzedpolymerization syrup was then poured into molds of variousconfigurations and thicknesses and allowed to cure for about 30 minutesat ambient temperature and pressure. The exotherm temperature wasmonitored during curing and it was noted that the thicker the mold, thehigher the peak exotherm temperature.

After curing, the articles were removed from the molds and examined.Each of the articles exhibited improved color, optical clarity andimpact resistance. Further, the thick articles were substantially bubblefree, indicating no air entrapment during curing.

EXAMPLE IV

A polymerization syrup was prepared by admixing the followingconstituents:

7500 ml of methyl methacrylate monomer

1200 ml of ε-caprolactam monomer

30 ml of isooctyl-3-mercaptopropionate

30 ml of allylmethacrylate

The resulting mixture was a substantially homogeneous blend and wasmaintained at ambient temperature and atmospheric pressure for about 78hours so as to provide a polymerization syrup having a viscosity ofabout 330 centipoise. When the desired viscosity had been achieved,(i.e., 330 centipoise), the polymerization syrup was then stabilized bythe addition of 15 ml tris-(2-chloroethyl) phosphite, a polymerizationinhibitor; and 40 ml of 2-(2'-hydroxy-5-methylphenyl)benzotriazole wasthen added to the polymerization syrup to enhance ultraviolet lightstabilization.

10 grams of a catalyst initiator containing 4 parts by weight ofN,N-dimethylacetoacetamide and 1 part by weight of benzyl-C12-18-alkyldimethyl isopropanol (a quaternary ammonium compound) was admixed intothe polymerization syrup. 27 pounds of aluminum trihydrite filler wasthen shear mixed into the polymerization syrup so as to provide ahomogeneous blend containing 60 weight percent of the filler and 40weight percent of the polymerization syrup.

The aluminum trihydrate employed as the filler had an average particlesize ranging from 1 micron to about 50 microns. That is, the aluminumtrihydrate contained 30 weight percent having an average particle sizeof 45 to 50 microns, 60 weight percent having an average particle sizeof 15-20 microns and 10 weight percent have a particle size of about 1micron.

The shear mixing was carried out until a substantially homogeneous blendof the polymerization syrup and the aluminum trihydrate was achieved.Thereafter, the homogeneous blend was subject to a wetting out period of30 minutes under a vacuum of 20 inches of mercury so as to removeentrapped air resulting from the shear mixing of the polymerizationsyrup and the aluminum trihydrate.

The vacuum was then removed and the homogeneous blend substantially freeof air was catalyzed by the addition of 126 grams of a catalystcontaining 90 weight percent t-butylperoxymaleic acid, 5 weight percent2-2-azobisisobutylnitrile and 5 weight percent silicon. Care was takento insure that the catalyst was uniformly dispersed.

The resulting resin was then poured, at room temperature, into a sinkmold and the mold was then sealed. The resin was allowed to cure atambient temperature and atmospheric pressure for 90 minutes. Theexotherm temperature of the resin was monitored during the curing ofsame. A peak exotherm temperature of 205° F. was obtained after thirtyminutes. At the end of 90 minutes the cured sink self-released from themold.

The sink was thereafter removed from the mold and tested using a thermalshock test procedure wherein the sink is repeatedly subjected to cyclesof hot and cold water. At the completion of 5400 cycles a matrix crackwas observed. However, the standard in the industry for such thermalshock testing is that a material suitable for use as tubs, sinks and thelike must withstand 500 cycles for the material to be acceptable in thefabrication of sinks, bath tubs and the like.

EXAMPLE V

A polymerization syrup was formulated in accordance with the procedureof Example I except that the polymerization of the monomers was allowedto continue for a period of about 80 hours so that the polymerizationsyrup had a viscosity of about 820 centipoise. 2 grams of a foamingagent, i.e. calcium hydroxide, was then admixed with 115 grams of thecatalyst activated polymerization syrup, followed by the addition of 1gram of N,N- dimethyl acetoamide to initiate the polymerization syrup.

Surfactants were then added to the initiated syrup. The surfactantsadded were 3.2 grams of sodium dioctyl sulfosuccinate, 0.40 grams ofpolyoxyethylene-polyoxypropylene glycol, and 1.5 grams of aflurochemical surfactant. The surfactants and the initiated syrup wereadmixed at ambient temperature and pressure to form a homogenous blend;and then 8.8 grams of glass beads filler was added to the homogeneousblend of the initiated polymerization syrup and surfactants.

The resulting particulate filled mixture was then catalyzed by theaddition of 1.8 grams of t-butyl peroxymaleic acid. The catalyzedmixture was thoroughly admixed and then poured into a mold at ambienttemperature and pressure.

The foamed resinous composition was removed from the mold after curing;and exhibited excellent skin. Additionally, the foamed resinouscomposition was exceptionally lightweight and exhibited good stainresistance.

EXAMPLE VI

A polymerization syrup was formulated in accordance with the procedureof Example I except that the polymerization of the monomers was allowedto continue for a period of about 79 hours so that the polymerizationsyrup had a viscosity of about 720 centipoise. The followingconstituents were shear mixed into 126 grams of the polymerizationsyrup:

1.5 grams of calcium hydroxide

1.0 grams of N,N-dimethyl acetoamide

2.1 grams of N-vinyl-2-pyrrolidone

1.5 grams of 2,4,7,9-tetramethyl-5-decyne-4,7-diol(126-86-3) ethyleneglycol

15 grams of tris-(2-chloroethyl) phosphite

126 grams of tri-hydrate

14.4 grams of glass beads

6.04 grams of t-butyl peroxymaleic acid

The resulting mixture foamed full and the filled foamed resinouscomposition exhibited excellent fire retardant properties. That is, thefilled foamed resinous composition, when tested in a flame tunnel,qualified to be classified in the UL class. Further, the filled foamedresinous composition had a flame spread of 143.

EXAMPLE VII

A polymerization syrup was formulated in accordance with the procedureof Example I except that the polymerization of the monomers was allowedto continue for a period of about 79 hours so that the polymerizationsyrup had a viscosity of about 650 centipoise. 1.0 grams of aninitiator, N,N-dimethyl acetoamide, was admixed with 115 grams of thepolymerization syrup; and thereafter, 0.95 grams of2,4,7,9-tetramethyl-5-decyne-4,7-diol (126-86-3) ethylene glycol and 0.3grams of polyoxyethylene-polyoxypropylene glycol were admixed into theinitiated polymerization syrup to form a homogenous initiatedpolymerization syrup.

1.3 grams of a foaming agent, i.e. calcium hydroxide, was then admixedinto the homogeneous initiated polymerization syrup, followed by theaddition of 5 grams of a fluorochemical surfactant. The resultingmixture was mixed until a homogenous blend was formed.

95 grams of a filler, terra alba gypsum, was then admixed into thehomogeneous blend; once the initial filler had been substantiallyuniformily dispersed throughout the homogeneous blend, 4.8 grams ofglass beads, was then added.

The resulting particulate filled polymerization mixture was catalyzed bythe addition of 4 grams of t-butyl peroxymaleic acid. The catalyzedparticulated filled polymerization mixture was then shear mixed atambient temperature and pressure. The resulting blended mixture was thenpoured into a mold to foam and cure.

The foamed polymeric resin so produced exhibited excellent strength,fire resistance and further exhibited the ability to be nailed and tohold a screw.

From the foregoing, it is clear that acrylic/lactam monomer basedpolymeric resins prepared by the activation of the polymerization syrupof the present invention exhibit improved color, optical clarity andimpact resistance, while at the same time possessing desired propertieswhich allow such resin compositions to be foamed, filled withparticulate fillers or cast into thick articles without air entrapment.

Thus, the present invention is well adapted to carry out the objects andattain the ends and advantages mentioned therein. While presentlypreferred embodiments of the invention have been described for purposesof this disclosure, numerous changes may be made which will readilysuggest themselves to those skilled in the art and which are encompassedwithin the spirit of the invention disclosed and as defined in theappended claims.

What is claimed is:
 1. A method for producing a particulate filledarticle comprising:admixing from about 10 to about 90 parts by weight ofa particulate filler material with from about 90 to about 10 parts byweight of a polymerization syrup to form a substantially homogeneousblend, the polymerization syrup formed by the steps of:admixing, atambient temperature, from about 300 to about 2970 parts by volume of anacrylic monomer represented by the formula ##STR2## wherein R is analkyl moiety containing 1 to about 18 carbon atoms, from about 30 toabout 2700 parts by volume of a lactam monomer containing from 3 toabout 12 carbon atoms in the lactam ring, from about 0.03 to about 40parts by volume of a mercaptan chain transfer agent and from about 0.03to about 40 parts by volume of a crosslinking agent capable ofcrosslinking the acrylic monomer and the lactam monomer so as to form asubstantially homogeneous blend; removing entrapped air from thehomogeneous blend; catalyzing the homogenous blend substantially void ofentrapped air; and curing the catalyzed homogeneous blend.
 2. The methodfor producing a particulate filled article of claim 1 wherein the fillermaterial has a particle size in the range of from about 1 micron toabout 200 microns.
 3. The method of claim for producing a particulatefilled article of claim 1 which further includes admixing into thepolymerization an effective amount of an inhibitor capable of preventingadditional crosslinking of polymeric constituents present in thepolymerization syrup when the desired viscosity of the polymerizationsyrup has been achieved.
 4. The method for producing a particulatefilled article of claim 3 wherein the filler material has a particlesize in the range of from about 1 micron to about 200 microns.
 5. Themethod for producing a particulate filled article of claim 4 wherein theeffective amount of the inhibitor present in the polymerization syrup isfrom about 0.05 to about 20 parts by volume.
 6. The method for producinga particulate filled article of claim 5 wherein the inhibitor isselected from the group consisting of methylethylhydroquinone,2,2-hydroxy-5-methylphenylbenzotriazole and alkyl phosphites.
 7. Themethod for producing a particulate filled article of claim 3 whichfurther includes incorporating into the polymerization syrup aneffective amount of an ultraviolet light stabilizer.
 8. The method forproducing a particulate filled article of claim 3 which further includesincorporating into the polymerization syrup from about 1 to about 20parts by volume of an ultraviolet light stabilizer.
 9. The method forproducing a particulate filled article of claim 3 which further includesincorporating into the polymerization syrup an effective minor amount ofan internal mold release agent.
 10. The method for producing aparticulate filled article of claim 3 wherein the acrylic monomerpresent in the polymerization syrup is methyl methacrylate and thelactam monomer present in the polymerization syrup is ε-caprolactam.